This invention relates generally to gas turbine engine fuel systems and, more particularly, to an improved prechamber and fuel manifold structure for gas turbine engines having premix-prevaporization type combustors.
In premixing-prevaporization type gas turbine engine combustors fuel is introduced into a prechamber ahead of the combustor reaction chamber in which prechamber it vaporizes in and mixes with a controlled quantity of pressurized air flowing through the prechamber to the reaction chamber. The subsequent combustion reaction which occurs in the combustor reaction chamber is characterized, at least in part, by the air-fuel ratio of the mixture formed in the prechamber so that by tailoring the air-fuel ratio the combustion reaction itself can, to varying degrees, be tailored. The degree of success achieved in tailoring the air-fuel ratio depends, again at least in part, on the ability of the fuel manifold to deliver precisely metered quantities of fuel to the prechamber and then on the ability of the prechamber to effect efficient vaporization and mixtures of the fuel. In one prior design, efficient fuel vaporization is promoted by multiple fuel delivery heads spraying or otherwise introducing fuel generally into the center of a prechamber through small metering orifices connected to larger fuel manifolds. In another proposal, fuel is injected into a cylindrical prechamber generally tangent to a wall of the prechamber and is immediately separated from the wall and atomized by air passing through the chamber. In still another proposal, a large number of swirl cans are disposed around an annular combustor, each swirl can having a fuel line extending from a remote manifold and delivering fuel generally tangent to a cylindrical surface of the swirl can. A prechamber and fuel manifold structure according to this invention represents an improvement over these and other known prechamber and fuel manifold structures.